METHOD AND APPARATUS FOR USING PRESSURE CYCLING AND COLD LIQUID CO2 FOR RELEASING NATURAL GAS FROM COAL AND SHALE FORMATIONS

摘要

The invention relates to a method and apparatus for sequestering C02 gas and releasing natural gas from underground coal and/or gas shale formations using C02 gas captured from the flue gas of a coal burning power plant, and processing it to produce cold liquid pressurized C02, and injecting the cold liquid C02 under pressure to create fractures within the formation and causing the C02 to be adsorbed into the coal or gas shale and CH4 to be desorbed, released and recovered. A special pressure cycling process is used to enable the pressure within the formation to be increased and decreased, including allowing the LC02 to change phase to a GL02, and injecting LC02 under pressure repeatedly, which causes greater expansion of the proliferation zone within the formation, and more efficiently releases CH4.